1. Field of the Invention
The present invention relates to an image pickup apparatus capable of acquiring a refocus image.
2. Description of the Related Art
In recent years, image pickup apparatuses have been proposed which perform a calculation for data acquired by an image pickup element and digital image processing according to the calculation to output a variety of images. The literatures Ren Ng, et al., “Light Field Photography with a Hand-held Plenoptic Camera”, 2005 Computer Science Technical Report CTSR, Todor Georgiev, et al., “Superresolution with Plenoptic 2.0 Camera”, 2009 Optical Society of America, and Aaron Isaksen, et al., “Dynamically Reparameterized Light Fields”, ACM SIGGRAPH, pp. 297-306 (2000) disclose image pickup apparatuses that simultaneously acquire a two-dimensional intensity distribution of light and angle information of a ray in an object space. The two-dimensional intensity distribution of light and the angle information of the ray are hereinafter collectively referred to as a “light field”, and acquiring the light field enables the acquisition of three-dimensional information on an object space. The image pickup apparatuses described above can change a focus position of an image, which is referred to as “refocusing”, change a shooting viewpoint, adjust a depth of field, and perform like operations, by acquiring the light field and performing the image processing after shooting the image.
Japanese Patent Laid-Open No. (“JP”) 2011-109310 discloses a configuration which utilizes a refocus function as an auxiliary function for autofocusing. JP S59-146029 discloses a configuration which shoots an image with a focus position being displaced depending on a depth of field determined by an aperture stop such that a plurality of objects are included within the depth of field.
While it is possible to change a focus position by the refocus function after a shooting, the focus position cannot be necessarily set to an arbitrary position because a range within which the focus position can be changed is limited. This may prevent a user, after the shooting, from changing a focus position to another point intended by the user. This means that a plurality of arbitrary objects cannot be included together in a refocus range with the configuration disclosed in JP 2011-109310. Similarly, it is impossible to generate a refocus image with the configuration disclosed in JP S59-146029.